1. Field of the Invention
The present invention relates to the recovery of rare earth values from rare earth containing minerals, and, more especially, to the recovery of rare earth values from minerals having but minor amounts of the rare earths contained therein. 2. Description of the Prior Art
At the present time, the rare earths are principally recovered by the processing of such minerals as monazite, bastnasite and xenotime. Other than these particular ores, which are the highest in rare earth contents, there exist numerous other minerals containing far lesser amounts of the rare earths, the exploitation and processing of which has not been economical to date. Particularly representative of such "poorer" minerals are those containing apatite, which have a content by weight of the rare earths, expressed as the oxides thereof, of less than 0.1%.
If a mineral has a low content of the rare earth elements, it is necessary to first enrich it by subjecting it to a physical treatment, e.g., gravimetry, flotation or magnetic separation. Such a process, which is in addition to the chemical treatment required to recover the rare earth elements, is expensive and seriously adversely affects the economics of the process.